1. Field of the Invention
The present invention relates to methods for manufacturing wiring modules provided with electronic circuit parts used in electronic instruments, electric instruments, computers, communication instruments, and the like.
2. Description of the Related Arts
In general, wiring modules are produced by mounting semiconductors such as LSIs, various electronic circuit parts, and the like on a printed circuit board. These wiring modules are used in electronic instruments such as computers. Various printed circuit boards in which the electronic circuit parts are mounted are known, including those formed using ceramics, those formed using a composite material of a reinforcing material such as glass fibers and a synthetic resin such as an epoxy resin, and those formed using a flexible film such as a polyester resin or an aramid resin. With respect to the number of circuit layers on the same surface of a double-faced board or a single-faced board, the circuit boards are divided into those with a single layer and those with multiple layers. The printed circuit boards are adopted in accordance with applications or required characteristics. All these printed circuit boards have a conductor circuit. The circuit pattern of each of these circuit boards has an increased density owing to the reduced size of the instrument and the improved performance of semiconductors.
Proposals have been made of, for example, a method for manufacturing a printed circuit board and a method for forming a wiring board provided with electronic circuit parts, both using an applied ink jet technique. Japanese Patent Laid-Open No. 11-163499 stacks conductor layers on a base material to form a printed circuit board. According to Japanese Patent Laid-Open No. 59-111385, wiring is applied directly to parts arranged on a base material.
However, with both the manufacturing methods described in Japanese Patent Laid-Open Nos. 11-163499 and 59-111385 using the applied ink jet technique, various electronic circuit parts are two-dimensionally arranged on the base material. Thus, the mounting density of electronic circuit parts cannot be increased in accordance with the reduced size of the instrument to which the circuit board is applied and the improved performance and reduced sizes of semiconductor elements.
In special cases, semiconductor chips need to be densely arranged as in small-sized memory cards. Thus, a proposal has been made of a method for three-dimensionally arranging electronic circuit parts. However, the presently proposed method for three-dimensionally arranging electronic circuit parts is effective only for stacking of a plurality of electronic circuit parts of the same shape such as memory chips. Disadvantageously, this method also increases mounting costs. Thus, the application of the conventional mounting methods is severely limited.